A 35-year-old patient comes to clinic because he has a worsening rash. He has had a rash in the past on his elbows and knees, but after finishing a "steroid pill" for his asthma his rash suddenly got worse. He also repos fevers and chills. On examination he has erythema involving 90% of his body surface area and there are some small pustules on top of the erythema on his trunk. What his the diagnosis?